Remove unused Autoconf checks for socket structs

[petk]

• struct cmsghdr is not used in the Swoole code
• the sockaddr_storage.ss_family used to be checked for AIX versions 5.3 and older, which contained __ss_family instead. On AIX 6 and later the ss_family field is available.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (9c08e1a) 72.97% compared to head (e8fe7e6) 72.93%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5253 +/- ## ========================================== - Coverage 72.97% 72.93% -0.05% ========================================== Files 69 69 Lines 14858 14858 ========================================== - Hits 10843 10836 -7 - Misses 4015 4022 +7 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.